From 0c70fda6c259e31df598bdcc7fb6673cdcb74f7a Mon Sep 17 00:00:00 2001
From: Simon Conseil <contact@saimon.org>
Date: Mon, 19 Feb 2018 23:33:47 +0100
Subject: [PATCH] Add source file for echo

---
 sigal/themes/photoswipe/static/echo/echo.js | 135 ++++++++++++++++++++
 1 file changed, 135 insertions(+)
 create mode 100644 sigal/themes/photoswipe/static/echo/echo.js

diff --git a/sigal/themes/photoswipe/static/echo/echo.js b/sigal/themes/photoswipe/static/echo/echo.js
new file mode 100644
index 0000000..f9fc98e
--- /dev/null
+++ b/sigal/themes/photoswipe/static/echo/echo.js
@@ -0,0 +1,135 @@
+/*! echo-js v1.7.3 | (c) 2016 @toddmotto | https://github.com/toddmotto/echo */
+(function (root, factory) {
+  if (typeof define === 'function' && define.amd) {
+    define(function() {
+      return factory(root);
+    });
+  } else if (typeof exports === 'object') {
+    module.exports = factory;
+  } else {
+    root.echo = factory(root);
+  }
+})(this, function (root) {
+
+  'use strict';
+
+  var echo = {};
+
+  var callback = function () {};
+
+  var offset, poll, delay, useDebounce, unload;
+
+  var isHidden = function (element) {
+    return (element.offsetParent === null);
+  };
+  
+  var inView = function (element, view) {
+    if (isHidden(element)) {
+      return false;
+    }
+
+    var box = element.getBoundingClientRect();
+    return (box.right >= view.l && box.bottom >= view.t && box.left <= view.r && box.top <= view.b);
+  };
+
+  var debounceOrThrottle = function () {
+    if(!useDebounce && !!poll) {
+      return;
+    }
+    clearTimeout(poll);
+    poll = setTimeout(function(){
+      echo.render();
+      poll = null;
+    }, delay);
+  };
+
+  echo.init = function (opts) {
+    opts = opts || {};
+    var offsetAll = opts.offset || 0;
+    var offsetVertical = opts.offsetVertical || offsetAll;
+    var offsetHorizontal = opts.offsetHorizontal || offsetAll;
+    var optionToInt = function (opt, fallback) {
+      return parseInt(opt || fallback, 10);
+    };
+    offset = {
+      t: optionToInt(opts.offsetTop, offsetVertical),
+      b: optionToInt(opts.offsetBottom, offsetVertical),
+      l: optionToInt(opts.offsetLeft, offsetHorizontal),
+      r: optionToInt(opts.offsetRight, offsetHorizontal)
+    };
+    delay = optionToInt(opts.throttle, 250);
+    useDebounce = opts.debounce !== false;
+    unload = !!opts.unload;
+    callback = opts.callback || callback;
+    echo.render();
+    if (document.addEventListener) {
+      root.addEventListener('scroll', debounceOrThrottle, false);
+      root.addEventListener('load', debounceOrThrottle, false);
+    } else {
+      root.attachEvent('onscroll', debounceOrThrottle);
+      root.attachEvent('onload', debounceOrThrottle);
+    }
+  };
+
+  echo.render = function () {
+    var nodes = document.querySelectorAll('img[data-echo], [data-echo-background]');
+    var length = nodes.length;
+    var src, elem;
+    var view = {
+      l: 0 - offset.l,
+      t: 0 - offset.t,
+      b: (root.innerHeight || document.documentElement.clientHeight) + offset.b,
+      r: (root.innerWidth || document.documentElement.clientWidth) + offset.r
+    };
+    for (var i = 0; i < length; i++) {
+      elem = nodes[i];
+      if (inView(elem, view)) {
+
+        if (unload) {
+          elem.setAttribute('data-echo-placeholder', elem.src);
+        }
+
+        if (elem.getAttribute('data-echo-background') !== null) {
+          elem.style.backgroundImage = "url(" + elem.getAttribute('data-echo-background') + ")";
+        }
+        else {
+          elem.src = elem.getAttribute('data-echo');
+        }
+
+        if (!unload) {
+          elem.removeAttribute('data-echo');
+          elem.removeAttribute('data-echo-background');
+        }
+
+        callback(elem, 'load');
+      }
+      else if (unload && !!(src = elem.getAttribute('data-echo-placeholder'))) {
+
+        if (elem.getAttribute('data-echo-background') !== null) {
+          elem.style.backgroundImage = "url(" + src + ")";
+        }
+        else {
+          elem.src = src;
+        }
+
+        elem.removeAttribute('data-echo-placeholder');
+        callback(elem, 'unload');
+      }
+    }
+    if (!length) {
+      echo.detach();
+    }
+  };
+
+  echo.detach = function () {
+    if (document.removeEventListener) {
+      root.removeEventListener('scroll', debounceOrThrottle);
+    } else {
+      root.detachEvent('onscroll', debounceOrThrottle);
+    }
+    clearTimeout(poll);
+  };
+
+  return echo;
+
+});